SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34e439f0b9227b660c9cf3632a78815ee25612abd225e8ccdb7c8844b2a53a48' 
  AND token = 'K3/g9u0m8YmjhLAWEQCS/gAiBcPvUV4LkbmGKbiVv+A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}